This invention relates to a process for treating a zeolite-containing cracking catalyst with an aqueous solution comprising an antimony compound so as to make the catalyst more resistant to the detrimental effects of metal poisons deposited thereon during catalytic cracking of hydrocarbon-containing oils. In another aspect, this invention relates to zeolite-containing cracking catalyst having been impregnated with an aqueous solution comprising an antimony compound. In a further aspect, this invention relates to a process for catalytically cracking a hydrocarbon-containing oil which contains metal impurities, wherein an aqueous solution comprising an antimony compound, is injected into the oil feed or, alternatively, into the cracking zone. In still another aspect, this invention relates to a process comprising catalytically cracking a metal-contaminated hydrocarbon-containing oil, separating cracked products from spent catalyst, and regenerating the spent catalyst for recycle to the catalytic cracking zone, wherein an aqueous solution comprising an antimony compound is injected into a catalyst regeneration zone.
It is well known to use antimony compounds as passivating agents for zeolite-containing cracking catalysts so as to mitigate the detrimental effects of metal poisons (primarily nickel/vanadium compounds) deposited thereon. Some of these antimony compounds are water soluble, such as those disclosed in U.S. Pat. Nos. 3,711,422; 4,595,771; 4,595,772 and 4,609,747. It is frequently more practical to employ an aqueous solution of an antimony compound as passivating agent rather than a solution of an antimony compound in a flammable organic solvent, especially if the passivating agent is to be injected into a hot oxidative catalyst regeneration zone. The use of aqueous solution essentially eliminates the danger of an explosion which exists when a highly flammable solution is used. The present invention is directed to the use of an aqueous solution comprising an antimony compound which is more effective than known aqueous antimony-containing metal passivating agents. The term "metals passivating", as used herein, implies that the detrimental effects during catalytic cracking (in particular excessive hydrogen generation and/or lower gasoline yields) caused by metal deposits (such as compounds of Ni, V and Cu) on a cracking catalyst composition have been mitigated.